Identd

The Ident service as specified by RFC 1413 is mostly used by various IRC networks and the occasional old FTP server to ask a remote server which user is making a connection.
This method is quite untrustworthy, as the remote host can simply choose to lie.

So you have two choices:

Tell the truth (see pidentd below)

Tell a little white lie (see nullident below)

pIdentd

Like most people, I prefer to run identd from from inetd instead of as a stand-alone service. For this to work you will need to install two packages: xinetd and pidentd. I tried this with oidentd but it does not seem to work with the latest xinetd.